(Reuters) - Japan's Elpida Memory Inc said it filed for protection from creditors on Monday with 448 billion yen ($5.55 billion) in debt, the biggest bankruptcy filing by a Japanese manufacturer.

The filing suggested that a possible rescue by domestic lenders and would-be overseas equity partners had stalled, the Nikkei newspaper said. Japan's sole maker of dynamic random-access memory (DRAM) chips has been hobbled by weak prices after a surge in demand for Apple Inc's iPad, which is much less reliant on DRAM chips than conventional PCs. It was also saddled with heavy capital spending to keep pace with well-funded South Korean rivals Samsung Electronics Co and Hynix Semiconductor Inc, while a strong yen hurt its global competitiveness. The filing raised concerns that the curtain could be lowered on Japan in the PC memory chip business that it once dominated.

"The bankruptcy protection will not mean that Elpida will stop producing chips immediately, but Elpida is shrinking and major customers will defect from the company and move to South Korean companies, which means more market share for the latter," said Lee Seung-woo, an analyst at Shinyoung Securities in Seoul.